While a silicon (Si) single crystal is widely used as a material of a semiconductor device, there have recently been developed semiconductor devices in which a highly heat-resistant semiconductor material such as silicon carbide (SiC), gallium nitride (GaN), and diamond is used (for example, refer to Patent document 1). These semiconductor devices are lower in transport current loss and are higher in switching frequency than a conventional Si-made semiconductor device. Moreover, temperatures suitable for operating a semiconductor device made of such a heat-resistant material properly (hereafter referred to as “operating temperatures”) are higher than the operating temperatures of an Si-made semiconductor device (approximately 15° C. to 120° C.) (the operating temperatures of an SiC-made semiconductor device: approximately 300° C. to 500° C.). It is therefore to be expected that a semiconductor device made of such a heat-resistant material will be utilized as a power semiconductor device through which a large electric current passes.
However, since such a highly heat-resistant semiconductor device is higher than a conventional Si-made semiconductor device in terms of operating temperature range, when it is housed in a conventional package before use, it will be very difficult to set the internal temperature of the package at the operating temperature of the semiconductor device. Hence, a new-type package has been sought after that can be readily set for a range of temperatures at which a highly heat-resistant semiconductor device can be operated in a proper fashion.